| Abstract: | Rechargeable lithium-oxygen(Li-O_2)batteries have appeal to enormous attention because they demonstrate higher energy density than the state-of-the-art Li-ion batteries.Whereas,their practical application is impeded by several challenging problems,such as the low energy round trip efficiencies and the insufficient cycle life,due to the cathode passivation caused by the accumulation of discharge products.Developing efficient catalyst for oxygen reduction and evolution reactions is effective to reduce the overpotentials in Li-O_2cells.In our work,we report a Co_3O_4modified Ag/g-C_3N_4nanocomposite as a bifunctional cathode catalyst for Li-O_2cells.The g-C_3N_4substrate prevents the accumulation of Ag and Co_3O_4nanoparticles and the presence of Ag NPs improves the surface area of g-C_3N_4and electronic conductivity,significantly improving the oxygen reduction/evolution capabilities of Co_3O_4.Due to a synergetic effect,the Ag/g-C_3N_4/Co_3O_4nanocomposite demonstrates a higher catalytic activity than each individual constituent of Co_3O_4or Ag/g-C_3N_4for the ORR/OER on as catalysts in Li-O_2cells.As a result,the Ag/gC_3N_4/Co_3O_4composite shows impressive electrochemical performance in a Li-O_2battery,including high discharge capacity,small gap between charge and discharge potential,and high cycling stability. |
